S H 



THE CULTIVATION OF THE TURBOT 



From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 
Proceedings of the Fourth International Fishery Congress : : Washi7igto7i, igo8 




WASHINGTON :::::; GOVERNMENT PRINTING OFFICE 




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THE CULTIVATION OF THE TURBOT 



From BULI.ETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 

Proceedings of the Fourth Internationat Fishery Congress : : JVashi?igton, ipoS 




VAaa- vVurv' 



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WASHINGTON 



GOVERNMENT PRINTING OFFICE :::::: 1910 



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BUREAU OF FISHERIES DOCUMENT NO. 686 
Issued April, 1910 



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THE CULTIVATION OF THE TURBOT 



By R. Anthony, D. Sc. 

Assistant Director, Laboratory of the Museum of Natural History 
(Pans) at St. V aast-la-Hougus 



Paper presented before the Fourth International Fishery Congress 
held at Washington, U. S. A., September 22 to 26, 1908 



859 



THE CULTIVATION OF THE TURBOT. 

By R. ANTHONY, D. Sc, 
Assistant Director, Laboratory of the Museum of Natural History {Paris) at St. Vaast-la-Hougue. 

[Translated from the French.] 

The question of marine pisciculture has been for some thirty years a subject 
of important concern to naturahsts. The present crisis in marine fisheries and 
the necessities involved seem to cause an increase of efforts in this direction. 

The term marine pisciculture serves to designate either natural pisciculture 
or artificial pisciculture (piscifacture) , both public and private or industrial. 

The so-called natural pisciculture is the simple operation of making the 
young edible fishes hatched at sea enter marine ponds or artificial reservoirs 
communicating with the sea, there to be fattened and then captured for market 
when they have attained a commercial size. Practiced for centuries, its develop- 
ment did not demand any previous knowledge of the phenomenon of repro- 
duction of the fishes. But it does demand the reahzation of natural conditions 
which are very special as to localities and surroundings, a thing which pre- 
vents it from becoming general. 

To this pisciculture, rudimentary to a certain extent, may be opposed the 
so-called artificial pisciculture, or piscifacture, thus named because the eggs 
and larvse are obtained in captivity. 

Artificial pisciculture may pursue either of two aims: It may be a public 
enterprise, an undertaking of the government, as a government alone can enter 
upon such an operation, its aim then the repopulation of the sea; on the other 
hand, it may be a strictly private enterprise to inaugurate an industry which 
would pursue the aim of breeding certain edible sea fishes in captivity for profit. 

The first attempts at artificial pisciculture were public undertakings; the 
aim was to attain the breeding of edible shore fishes in captivity, to have the 
eggs hatch, and to deposit the larvae at a point on the coast where a decrease 
of these fishes had been noticed. The young fishes were released in the sea 

86i 



862 BULLETIN OF THE BUREAU OF FISHERIES. 

a few days after they were hatched, before the entire disappearance of the yolk 
sac and the beginning of feeding by external means. The Government of the 
United States was the first to interest itself in this question of such important 
general concern, by founding in 1878 at Gloucester, in the state of Massachusetts, 
in the vicinity of the great city of Boston, the first pubHc estabhshment for 
marine pisciculture. The establishment at Gloucester was soon followed by 
one at Provincetown, one at Woods Hole, and one on the steamer Fish Hawk. 
In 1883 Norway followed the example of the United States and created the 
establishment of pisciculture at Flodevig. In 1889 the Government of New- 
foundland founded the establishment of Dildo and, lastly, in 1894, Great Britain 
founded, thanks to the Fishery Board of Scotland, the establishment of Dunbar. 
These various establishments gave each year to the sea several thousands of 
cod, plaice, and even turbots, hatched in captivity; it must nevertheless be 
said that it was never possible to obtain at Dunbar, the only establishment 
where the replenishing of coastal waters with turbots was attempted, any 
natural hatching of this fish, and that it was always necessary to have recourse 
to artificial stripping and fertilization as practiced for the fresh-water fishes. 

It is not our aim to discuss, after so many others have done so, the question 
of the real utility of marine pisciculture for the replenishment of the sea. Let 
us merely remember from the experiments of our predecessors this very 
important fact: It is due to their efforts that at the present time we have 
been able to obtain natural spawning in captivity and the hatching of eggs of 
the greater number of edible coastal fishes having pelagic eggs. 

For some twelve years French naturalists seem to have devoted themselves 
to private or industrial artificial pisciculture. In other words, the work done 
to-day is an attempt at the entire process of breeding edible fishes from the 
egg until they reach a commercial size, to create thus a real industry which 
may in future become an actual source of riches. The first step in the new 
direction was made by Mr. Edmond Perrier, Director of the Museum of Natural 
History, Member of the Institute, and director of the maritime laboratory of 
St. Vaast-la-Hougue, who has the great merit of having been the first to appre- 
ciate the importance of the problem and to establish at his laboratory a com- 
plete equipment for industrial marine pisciculture. 

It will be remembered that without an}' thought as to its industrial value 
and for purely scientific purposes, Meyer had been breeding the herring since 
1878; at Flodevig young cods were bred, at Plymouth young flounders, and at 
Concarneau young bullheads; at Dunbar, Harald Dannevig had succeeded in 
breeding young plaice. In addition to the fact that the industrial point of view 
was entirely overlooked in these experiments, species of smallor no commercial 
value were experimented upon. 



CULTIVATION OF THE TURBOT. 863 

Before attempting marine pisciculture it is necessary to ask oneself what 
are the fishes for which such experiments would be practically profitable. It is 
evident that migratory fishes, or those living in depths the natural conditions 
of which we can not offer them in captivity, are to be eliminated. Moreover, 
before attempting the breeding of nonmigratory fishes of commercial value 
there is a certain number of questions which ought to be answered: (i) Is the 
fish in question of sufficient commercial value to render its breeding profitable? 
(2) Is its growth in captivity sufficiently rapid, and is the cost of bringing it 
to its commercial size disproportionate to its market price? 

In the last analysis it will appear that among the fishes inhabiting our 
European waters there are only four species which are profitable objects of 
marine pisciculture. These are the sole {Solea vulgaris Quensel), the turbot 
{Rhombus maximus Linnaeus), the umbrina {Labrax lupus Cuvier), the surmul- 
let (Mullus surmuletus Linnaeus). According to Cunningham, the turbot at the 
age of two years is from 28 to 38 centimeters long, and reaches 60 centimeters at 
the age of four years. As to the sole, it reaches only 23 centimeters at the age 
of two years. 

Of all these various edible fishes, the most profitable from the point of 
breeding is the turbot, on account of its high price, its particularly rapid growth, 
its prodigious fecundity (the turbot yields about 9,000,000 eggs per year) and, 
lastly, its hardiness and the ease with which it may be fed and fattened. Un- 
fortunately, however, this species is the one the artificial reproduction of which 
presents the greatest difficulties, as was justly observed in 1905 by Fabre- 
Domergue and Bietrix, whose researches in this line go as far back as 1896." It 
must be remembered that no natural hatching of turbot could be accomplished 
at Dunbar and recourse was had to artificial methods of stripping and fecunda- 
tion, as for fresh-water fishes. 

The problem of industrial marine pisciculture must necessarily traverse 
two stages before reaching complete realization — a preliminary and purely 
scientific stage, and a final and really practical stage. 

The scientific success of the problem seems to consist in hatching a reason- 
able number of young fishes and keeping them in the laboratory beyond the 
critical stage. (As defined by Fabre-Domergue, the critical stage begins when 
the umbilical vesicle is entirely absorbed and the young fish begins to look for 
food among its surroundings.) Practical success consists in keeping a consider- 
able number of fishes until they acquire such condition that the operation may 
be really remunerative. It is evident that before attempting the study of the 
second feature of this problem the first must be solved. It is only when the 

a Fabre-Domergue and Bietrix; Le developpement de la sole, 1905. Travail du Laboratoire de 
Zoologie maritime de Concariieau. 



864 



BULLETIN OF THE BUREAU OF FISHERIES. 



first Stage shall have been passed that it will be legitimate to inquire whether 
the results obtained in the laboratory may or may not be repeated on a larger 
scale, i. e., to practical purpose, with perhaps a somewhat different technique. 
Practical marine pisciculture, the origin of which does not date further back 
than twelve years, is as yet in its scientific period. 

The two principal difficulties involved in the solution of the scientific problem 
are the following: (i) The obtaining in captivity of natural and normal hatches 
in as great numbers as might be desired, and the determination of the conditions 
of these hatches. (2) The feeding and the preservation of a reasonable number 

of larvae beyond the crit- 
ical period and under con- 
ditions such that the ex- 
periment may be repeated. 
As has been justly ob- 
served by Messrs. Fabre- 
Domergue and Bietrix 
(op. cit.), the incubation, 
hatching, and preserva- 
tion of the larvae until the 
beginning of the critical 
period do not present any 
difficulties. 

In the laboratories of 
pisciculture in America, 
Norway, and England the 
question of hatching in 
captivity has been solved 
for the plaice and for the 
cod, but could not be 
solved for the turbot, the 
only marine fish truly interesting from the point of industrial breeding. The 
passage through the critical period had not been attempted for any species in 
laboratories here cited, because the fishes were deposited in the sea before the 
beginning of this period. The principal object of practical marine pisciculture in 
recent years, then, in Europe at least, has been to obtain normal hatches of 
turbots in captivity and to carry their larvae past the critical period. 

It was at the laboratory of St. Vaast-la-Hougue that numerous normal 
hatches of turbots were obtained for the first time bv A. E. Malard in 1898." 




Fig. I. — Early development of the turbot. i. Fecundated egg; ii. egg with 
blastoderm; irt. egg with embryo, not pigmented, iv. egg with pigmented 
embryo; v. larva just after hatching; vi. larva with vitel us about half 
resorbed; vii, larva with vitellus almost entirely resorbed ; viii. larva in 
critical period, vitellus just resorbed; ix. larva at end of critical period, g, 
Oilglobule; &, blastoderm: e, embryo; t', vitellus; fr.moutli; o, anus; o, eye; 
p. axis of insertion of pectoral fin. 



" Malard, A. E, : Sur le developpement et la pisciculture du turbot, 
des Sciences, Paris, 17 juillet, 1899, 



Coniptes rendus de TAcad^mie 



CULTIVATION OF THE TURBOT. 865 

In 1904, L. Dantan," repeating these experiments, obtained an identical result 
at the same laboratory. In both cases the hatching took place normally, but 
unfortunately all the larvae died a few days later, not being able to survive the 
critical stage. Thus only the first part of the problem was solved. 

In 1905 Fabre-Domergue and Bietrix (op. cit.) published their memoir on 
the development of the sole. No hatches of turbot or sole could be obtained 
in the laboratory of Concarneau where these authors operated. Fabre- 
Domergue and Bietrix were obliged painstakingly to collect eyed eggs of the 
sole in the sea. But they were able to bring a small number of individuals far 
beyond the critical period. For the sole, at least, the second part of the scientific 
problem was realized. In 1905 Malard and Dantan, who had obtained normal 
hatches of the turbot, had not been able to carry their larvse past the critical 
period, and Fabre-Domergue and Bietrix, who had not been able to obtain 
hatches, had carried the sole through the critical period. With the turbot, 
rearing past the critical period had not been accomplished. 

In the course of 1907 we were more fortunate at the laboratory of St. Vaast- 
la-Hougue than in 1898 and in 1904, and succeeded not only in making the 
larvae live beyond the resorption of the umbilical sac, but in obtaining after this 
critical period a considerable increase of volume and an important modification 
of the shape. The conditions under which I obtained these results are the fol- 
lowing: 

During the month of February, 1907, I procured 10 adult turbots, which I 
placed in the large hatching basins of the laboratory. These basins, constructed 
according to the directions of Mr. Edmond Perrier, are three in number. The 
capacity of the largest is more than 300 cubic meters. They are filled by means 
of a pump, worked by a windmill, or a gasoline motor when the wind is not 
sufficiently strong. This pump brings the water to the upper part of the basin. 
A waste pipe is in the lower part. In the middle is an incomplete trench about 
the depth of a stair step, made after the design of A. E. Malard, to promote the 
spawning of the females, which this author found rubbed their abdomens against 
its acute angle. The basins are covered with a thatched roof and are amply 
lighted . 

Let us note that so far there exists no certain external means of recognizing 
the sex of the turbots when alive, although many naturalists have endeavored 
to find it. Nevertheless, taking 12 individuals, there are great chances of having 
both females and males among them. The only thing to remember is that the 
fish should not be less than 40 centimeters in length. With smaller individuals 
there would be a risk of their not yet being mature. 



" Dantan, L. : Notes ichthyologiques. Archives de Zoologie expdrimentale et generale. Notes 
et revues, 1905. 

B. B. F. 1908—55 



866 BULLETIN OK THE BUREAU OF FISHERIES. 

At the end of a few weeks of captivity our prisoners began to feed. To them 
were distributed once a week large pieces of plaice at the rate of about half a fish 
the size of the hand to each turbot. This ration may seem scant, but it was 
purposely limited, we deeming that too great an abundance of food is not favor- 
able to the functions of reproduction. It is probably to excess of feeding 
that must be attributed the failure of attempts to make the turbot spawn in 
captivity. In order to keep the basins free of putrefying food substances we put 
with our turbots a conger eel and a dogfish long since acclimated to life in cap- 
tivity. These fishes, well known for their voracity, were employed as scavengers, 
in which capacity they did good service. Our turbots, in captivity since Feb- 
ruary, began to spawn in July. 

We do not know yet whether individuals that have spawned in captivity 
and survived one season will spawn the following year. We will not know this 
until in July next. In any case it does not seem to us very important to know 
whether it is necessary to keep the same brood stock for one or more years, since 
fish captured only six months previously had ample time to get acclimated 
and have given excellent results. Let us add that it seems to us very imprudent 
to capture breeders only a few weeks before the spawning time. Not yet 
acclimated, they might exhibit phenomena of ovular retention, which are in 
most cases fatal. 

The first eggs were laid on July 1 8 , and were soon followed by four other lots. 
The dates of the consecutive spawnings were July i8, 21, 28, 29, and August 3. 
These lots of eggs numbered thousands and thousands, all normal and normally 
fertilized. A certain number only were carefully gathered by means of plankton 
nets and transferred to the incubation apparatus. An essential feature of this 
apparatus is continuous agitation, which is a very important thing in incubation, 
keeping the egg free of sediment and thus preventing asphyxiation. Dannevig, 
among others, at the station of Dunbar had already employed a complicated 
apparatus which provided continuous agitation. 

The apparatus used by us was that of Fabre-Domergueand Bietrix modified, 
which apparatus is in itself a modification of that constructed by Browne at the 
laboratory of Plymouth to preserve pelagic organisms alive. It consisted of a 
receptacle in which a plunging disk rose and fell by means of a special contrivance. 
In the apparatus of Fabre-Domergue and Bietrix the somewhat violent agitation 
produced by the vertical motion of the disk is replaced by a helicoidal movement, 
the disk being obliquely fixed on a vertical rotating axis and thus working like 
a screw. The apparatus is composed of 4 glass barrels of 50 liters capacity, 
each supplied with a revolving disk, and the 4 disks are worked by a small hot- 
air motor of -^^ horsepower. 



CULTIVATION OF THE TURBOT. 



867 



I thought it advisable to make a few modifications in the apparatus of 
Fabre-Domergue and Bietrix which seemed to me of great importance to the 
final success. On the thread of the vertical rod carrying the disk I attached 
above the level of the water, as tightly as possible, a small wad of absorbent 
cotton to take up and keep off the oil that might come from the wheels above it. 
I had observed that a small part of the oil could descend along this vertical 
glass rod and thus reach the water, where it formed a thin layer, the effect of 
which was hindrance of aeration, causing asphyxiation of the larvae. Below this 
wad I placed, upside down, the disk-shaped cover of a small vessel, thus to keep 
dust from falling into the water, without, however, 
hindering the circulation of the air. This disk was 
secured below by a second wad of cotton. I also 
utilized the lower, lateral, tubular outlet of the 
barrel to set up a tube within terminating at the 
top in a funnel covered with very fine silk, to allow 
the passage of water but not of lar\'ae. The open- 
ing of this funnel was the size of a 5-franc piece, 
and the flare thus obtained was designed to 
decrease, as far as possible, the intensity of the 
current, which, were it too violent, would cer- 
tainly have carried the larvae with it. This pos- 
sible carrying out of the larvse constitutes a real 
danger, against which, however, we are still better 
protected in the apparatus which we have had 
constructed for our experiments in 1908. 

Several times a day part of the water in the 
barrel was renewed for 10 minutes by means of a 
siphon, there being in the course of the supply 
tube a flaring inlet for the purpose of aeration. 
Several times a day also the bottoms of the basins were carefully siphoned 
to remove the dead eggs and all other matter that might pollute the water. 
These modifications, of details only, which we have made in the excellent 
apparatus in which Fabre-Domergue and Bietrix have been able to carry the 
sole past the critical stage ought to be considered an indication, so to speak, 
of more important modifications which will render possible its practical use 
on a larger scale than from the point of view of experiments only. 

The hatching of the eggs took place without difficulty and without hindrance 
between the sixth and eighth days after spawning. Two or three days after the 
appearance of the larvae, without waiting for the complete absorption of the 




Fig. 2. — Apparatus for hatching turbot 
(modification of apparatus of Fabre- 
Domergue and Bietrix) . a and b, wads of 
cotton ; c, upturned cover which serves as 
dust shield; d. inflow pipe' e, outflow pipe 
with screened funnel entrance ; /.revolv- 
ing disk for agitation of the water. 



868 BULLETIN OF THE BUREAU OF FISHERIES. 

yolk sac, and following in this the excellent advice given by Mr. Edmond Perrier 
in 1896, at the Congress of Fisheries at Sables d'Olonne, and a little later, in 
1898, by Mr. Fabre-Domergue, we began the feeding of our young larvae. Their 
diet was composed of live plankton collected in the open by means of fine-meshed 
nets, and carefully sifted upon arrival at the laboratory through very fine sifting 
silk, for the purpose of eliminating the organisms which might constitute a 
danger by their size or their nature. One distribution of plankton was made 
every day, and in great abundance. Moreover, the agitation of the water 
maintained the plankton alive, and the young fry had consequently always in 
reach a fresh live food as varied as under natural conditions of their life. Toward 
the fourteenth or fifteenth days the last trace of the sac disappeared, and about 
the eighteenth or twentieth day the critical period might be considered as passed. 
The young larvae had at that period taken the peculiar shape characterized by 
the widening of the head, and they fed normally. 

For the retention of the larvae after the beginning of the resorption of the 
yolk sac, i. e., during the critical stage, two things are necessary: (i) Continuous 
agitation of the water, and (2) appropriate food. Continuous agitation of the 
water is incontestably very useful in the incubation of the eggs and the normal 
life of the larvae up to the time when they begin to feed, but during these periods 
it is not, as later, absolutely indispensable. 

We have, in fact, found at St. Vaast, on the one hand, that the eggs which 
were left in our hatching basins developed there and hatched normally , and the 
larvae did very well until after the disappearance of the yolk sac ; on the other hand, 
the same facts were observed in the hatching aquaria. But what we did not 
accomplish, and we can not insist too much on this point, was to make larvae live 
even a few hours, though off'ering them plankton, under these conditions after the 
disappearance of their yolk sac. It is at this time, we believe, with all who have 
undertaken marine pisciculture, that continuous agitation of the water is abso- 
lutely necessary. Without it the young fish is never in the presence of its food, 
it weakens, falls to the bottom, and dies of hunger. 

As to feeding, let us recall that the fry were very precocious, and began to 
feed even before the complete disappearance of the yolk sac. The objection 
might be raised that plankton as the basis of food for the larvae can not be con- 
sidered for a moment where breeding on a large scale is to be undertaken. It 
may be said that on certain days storms disturb the sea, and the water being 
full of ooze and sand, collecting is impossible. We believe that we can say that 
the period during which plankton will be necessary is precisely during the 
season of the year in which storms are most rare (from July i to September 15, 
at the latest, for the region of St. Vaast-la-Hougue) . Should there be storms, 



CULTIVATION OF THE TURBOT. 869 

however, one would always have the resource of small plankton organisms in 
the pools left when the sea recedes. Moreover, the continuous agitation appa- 
ratus will allow us to keep alive a small reserve of plankton to supply the needs 
of our larvae for three to four days. And, lastly, one more argument, shall it 
be considered a priori impossible to breed certain plankton organisms, carefully 
selected? Continuous agitation apparatus would undoubtedly be suitable for 
this purpose likewise. The experiments of Bracque have almost solved this 
question already. I am not opposed a priori to a semiartificial food as, for 
example, the Monas dunali of marshes successfully employed by Messrs. Fabre- 
Domergue and Bietrix for feeding their larvae of soles, and it is even possible 
that this organism might be made to render the greatest service in marine pisci- 
culture. But it is nevertheless most true that it is in the great variety of 
plankton organisms that we shall find the food necessary for the normal feeding 
of the larvae of teleosts with pelagic eggs. I dared not experiment with purely 
artificial food, advised by others (cheese, shrimp meal, etc.). I believe that 
rapid putrefaction would occur. I believe, in short, that during the first period 
the best food would be small plankton organisms, carefully selected. 

Let us add that in hatching troughs the temperature of the water ought 
not to be above 20° C. We have operated constantly at a temperature of from 
18° to 20° C. It seemed best to have it from 15° to 20° C. Let us say, further, 
that during the critical period we lost only i individual in 10, a result which 
might be considered excellent, it seems to me. 

What is left to be done in the culture of the turbot? There remains to 
protect the young larvae from the end of the critical period to the end of the 
metamorphosis, since we are sure, and we have often shown by experiment, that 
there is nothing easier than to fatten young turbots and other pleuronectids, 
and make them grow. For this purpose it will be sufficient to substitute for 
the plankton, as rapidly as possible, fish flesh mashed into a pulp, this to be 
consecutively replaced by larger and larger pieces of fish as the size of the 
turbots increases. 

It remains likewise to carry marine pisciculture from the domain of science 
to industry, and this is not the least of the work to be done — to determine, in 
fact, whether the procedure applicable on a small scale in laboratories may be 
carried on on a larger scale. It is necessary to determine the price of the food 
required to fatten the fishes bred and to see if this price allows a profit, taking 
into consideration the market price per kilogram of the turbot. 

It is possible that the waste of fishes in the vicinity of great harbors might 
constitute a valuable resource for industrial marine pisciculture of the future. 



syo bulletin of the bureau of fisheries. 

Resume; and conclusion. 

The results obtained by us at the marine laboratory of St. Vaast-la-Hougue 
during the summer of 1907 are in brief the following: 

(i) After Messrs. Malard and Dantan we obtained natural, normal, and 
abundant hatches of turbot, a result which had been sought for twenty years 
in a great number of other marine laboratories. 

(2) We were the first to succeed in carrying the larvae of this pleuronectid 
through the critical period, the obstacle which hitherto all the naturalists study- 
ing pisciculture had been unable to overcome, and which seemed to be the prin- 
cipal rock in the course of marine pisciculture. 

(3) Throughout our work the mortality of the larvae may be said to have 
been a negligible quantity (about 10 per cent). 



BuL. U. vS. B. F., 1908. 



Plate CII. 




\ 




Fig. I.— Turbot t^gg^ with einbrj^o. Fourth day. 




Fic;. 2.— I^arva with vitelhis. Eighth day. 




Fig. 3. — I,an.'a with vitellus almost entirely resorhed— beginnintj ol the critical period. Tenth day. 



BuL. U. S. B. F., 1 90S. 



Pirate CIII. 




Fig. 4.— I,arva a few days after end of critical period, 
abdomen fnll of food. Sliape of fish changed. 




Fio. 5. — Detail of pigmentation of abdo 




ilit;il period (cadavL 



,GP£SS 




